1. Field of the Invention
This invention relates to flare ignition systems that may be used to ignite aircraft-launched parachute illuminating flares and may also be adapted for rocket deployment flares or other ordnance devices such as colored markers and gas generators. The invention is characterized by its provision of an ordnance safety feature that could possibly prevent catastrophic disasters (intense fires) tending to result from inadvertent or accidental ignition of the primer of the ignition system.
2. Description of the Prior Art
Many pyrotechnic devices such as military flares and rockets utilize the pulling of a lanyard to release a firing pin to effect ignition or to perform other functions that must executed after the pyrotechnic device clears a launcher or other hardware. A safety hazard exists with pyrotechnic devices of this type in that if a flare, for example, is dropped during handling or the lanyard inadvertently is caused to be pulled and the primer to be fired, a very serious accident can result.
In the prior art a number of proposals have been advanced for solving these problems. The patents and pending application discussed below are a representative sample of these proposals.
U.S. Pat. No. 2,392,884 granted Jan. 15, 1946 discloses a fuze for projectiles having safe and arm positions. There is included within the fuze body an unbalanced cylindrical detonator block which normally is held in a fixed safe position by a shear pin. Upon firing of the projectile, setback shears the shear pin and centrifugal force resulting from projectile rotation turns the unbalanced block to the armed position. In the armed position, a passage in the block allows flame and hot gas resulting from the impact of a firing pin and primer to communicate with a booster charge and thereby transmit detonation to a booster charge that fills the main body of the projectile. In the safe position, such communication is precluded by the unbalanced block.
A SAFE-ARM device for solid propellant rocket motors is disclosed in U.S. Pat. No. 3,529,418 granted Sept. 22, 1970. In this device there is provided a manually movable plug that in one position precludes accidental or inadvertent ignition of the motor, and in another position permits ignition of the motor on command. When in the safe position, the plug disperses to the atmosphere any gases or flame that result from accidental or inadvertent ignition, with spring tension means maintaining the plug in the safe position.
A similar SAFE-ARM device for solid propellant rocket motors is disclosed in U.S. Pat. No. 3,423,931 wherein the movable plug comprises a double ended piston that is movable in a tubular body and functions as a seal at either end of the body, with the toggle action of a spring maintaining the piston in the safe position.
An ignition system for air dropped illuminating flares triggered by the parachute shock pull on the ignition lanyard is disclosed in U.S. Pat. No. 3,736,877 granted on June 5, 1973. The ignition propellant is housed in plastic foam for protection and for absorbing the impact shock if the flare should inadvertently be dropped.
In U.S. Pat. No. 3,763,785 there is disclosed a safety device for an explosive train arming rotor type fuze comprising a dog that co-acts with the arming rotor to preclude mal-assembly of the fuze.
In copending U.S. application Ser. No. 485,083 filed Apr. 14, 1983 , now U.S. Pat. No. 4,483,250, assigned to the assignee of the present invention, there is disclosed a flare manual safety device comprising a cylindrical valve member that may be manually rotated, and in its safe position, forms a barrier between the firing pin-primer charge and the pyrotechnic ignition material for flares. The valving member has a passage through it that may be aligned with the firing pin-primer charge and the pyrotechnic ignition material in its armed position.
While there is recognition in the prior art, as above mentioned, of some of the desirable attributes of a flare ignition safety system or device, there remain problems with respect to locking the system in a safe condition and maintaining it in that condition to the end that accidental or otherwise unwanted firing of the primer during assembly and handling or caused by heat, shock or impact will not propagate to other ignition materials.